Nitrate is required to maintain the growth and metabolism of plant and animals. Nevertheless, in excess amount such as polluted water, its concentration can be harmful to living organisms such as microalgae. Recently, studies on microalgae response towards nutrient fluctuation are usually limited to lipid accumulation for the production of biofuels, disregarding the other potential of microalgae to be used in wastewater treatments and as source of important metabolites. Our study therefore captures the need to investigate overall metabolite changes via NMR spectroscopy approach coupled with multivariate data to understand the complex molecular process under high (4X) and low (1/4X) concentrations of nitrate (). NMR spectra with the aid of chemometric analysis revealed contrasting metabolites makeup under abundance and limited nitrate treatment. By using NMR technique, 43 types of metabolites and 8 types of fatty acid chains were detected. Nevertheless, only 20 key changes were observed and 16 were down regulated in limited nitrate condition. This paper has demonstrated the feasibility of NMR-based metabolomics approach to study the physiological impact of changing environment such as pollution to the implications for growth and productivity of microalgae population.

Mangrove-dwelling microalgae are well adapted to frequent encounters of salinity fluctuations across their various growth phases but are lesser studied. The current study explored the adaptive changes (in terms of biomass, oil content and fatty acid composition) of mangrove-isolated C. vulgaris UMT-M1 cultured under different salinity levels (5, 10, 15, 20, 30 ppt). The highest total oil content was recorded in cultures at 15 ppt salinity (63.5% of dry weight) with uncompromised biomass productivity, thus highlighting the ‘trigger-threshold’ for oil accumulation in C. vulgaris UMT-M1. Subsequently, C. vulgaris UMT-M1 was further assessed across different growth phases under 15 ppt. The various short, medium and long-chain fatty acids (particularly C20:0), coupled with a high level of C18:3n3 PUFA reported at early exponential phase represents their physiological importance during rapid cell growth. Accumulation of C18:1 and C18:2 at stationary growth phase across all salinities was seen as cells accumulating substrate for C18:3n3 should the cells anticipate a move from stationary phase into new growth phase. This study sheds some light on the possibility of ‘triggered’ oil accumulation with uninterrupted growth and the participation of various fatty acid types upon salinity mitigation in a mangrove-dwelling microalgae.

Interest in harvesting potential benefits from microalgae renders it necessary to have the many ecological niches of a single species to be investigated. This dataset comprises de novo whole genome assembly of two mangrove-isolated microalgae (from division Chlorophyta); Chlorella vulgaris UMT-M1 and Messastrum gracile SE-MC4 from Universiti Malaysia Terengganu, Malaysia. Library runs were carried out with 2 × 150 base paired-ends reads, whereas sequencing was conducted using Illumina Novaseq 2500 platform. Sequencing yielded raw reads amounting to ∼11 Gb in total bases for both species and was further assembled de novo. Genome assembly resulted in a 50.15 Mbp and 60.83 Mbp genome size for UMT-M1 and SE-MC4, respectively. All filtered and assembled genomic data sequences have been submitted to National Centre for Biotechnology Information (NCBI) and can be located at DDBJ/ENA/GenBank under the accession of VJNP00000000 (UMT-M1) and VIYE00000000 (SE-MC4).

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